The N-Squared Inter-Working Function (N2IWF) is a protocol adaptor providing network charging integration between a Diameter-capable Online Charging Server from Legacy and Next Generation network-side call and message control protocols:

For voice charging, the N-Squared Inter-Working Function can be deployed in one (or both) of the following modes:

• N2IWF-SIP - SIP INVITE ⇄ Diameter Credit Control
• N2IWF-SCP - CAMEL/INAP InitialDP ⇄ Diameter Credit Control

For short message (event) charging, the N-Squared Inter-Working Function supports handling of:

• SMPP including Huawei SMPP+
• CAMEL3/CAMEL4 InitialDPSMS ⇄ Diameter Credit Control
• Ericsson SCAP (RFC 3588 AAA Messages) ⇄ Diameter Credit Control

Note that the Inter-Working Function does not include any local subscriber database. Per-subscriber information is obtained at call-time via one or more of the following sources:

• From the OCS embedded within the Initial Credit-Control-Answer, or
• From the OCS or another server via a separate, dedicated Diameter request, or
• Via REST/SOAP/External-DB via client callout or DB lookup.

Documentation

Product Information

• N2IWF Product Summary (PDF Download)

User & Technical Guide

• N2SVCD Technical Guide (HTML Online) [Run-Time Components]
• N2SCP Technical Guide (HTML Online) [N2IWF-SCP Network-Side]
• N2SIP Technical Guide (HTML Online) [N2IWF-SIP Network-Side]
• All-Product Alarm Guide (HTML Online) [Alarms & Statistics]

Protocol Conformance Statements

• N2IWF Diameter Conformance (PDF Download)
• N2SCP CAMEL/INAP Conformance (PDF Download)
• N2SIP SIP-SDP-RTP Conformance (PDF Download)
• N2SVCD SIGTRAN-TCAP Conformance (PDF Download)

Supplementary Features

The core feature of the Inter-Working Function performs is charging of talk-time from the network-side protocol (SIP or CAMEL) into Diameter.

The N2IWF also provides support for supplementary, “value-add” features, including:

• Pre-Call and/or Post-Call Announcements (e.g. Balance Information, Account Status)
• Routing and re-direction logic

Logic can be based on site-specific supporting data, accessed via:

• REST client requests to external servers
• SOAP client requests to external servers
• Database lookup/update requests to external databases

Note that announcement support requires the deployment of a compatible media server, such as the N-Squared N2SRP Specialized Resource Platform.

When combined with other N-Squared components, the solution can also provide:

• Number portability lookup and translation (with N2SNS, Simple Number Services)
• Short-number lookup and translation (with N2CUG, Closed User Group)

Message Flows

N2IWF-SIP

The following diagrams show (simplified) SIP INVITE ⇄ Diameter message mappings.

Refer to the SIP Product Conformance Statements (link above) for a more detailed description of supported SIP call-control flows.

Pre-call/post-call announcements using SIP require the presence of an INAP-capable Intelligent Peripheral such as the N-Squared Specialized Resource Platform (N2SRP).

N2IWF-SCP

The following diagrams show (simplified) CAMEL/INAP InitialDP ⇄ Diameter message mappings.

Refer to the CAMEL/INAP Product Conformance Statement (link above) for a more detailed description of supported CAMEL/INAP call-control flows including support for CAP1, CAP2-CAP4, CS-1, CS-2, and some vendor-specific INAP message support.

Pre-call/post-call announcements using CAMEL/INAP require the presence of an INAP-capable Intelligent Peripheral such as the N-Squared Specialized Resource Platform (N2SRP).

N2IWF-SMS

The following diagrams show (simplified) CAMEL/INAP InitialDPSMS ⇄ Diameter message mappings.

Refer to the CAMEL/INAP Product Conformance Statement (link above) for a more detailed description of supported CAMEL/INAP call-control flows including support for CAP3 and CAP4, InitialDPSMS.

Deployment Notes

Platform Sizing

The solution is laterally scalable with N+1 deployment for High-Availability, Geographic Redundancy, and to support increased traffic growth.

OSS/BSS Features

A Graphical Interface is provided for platform maintenance.

Operational functions include Alarms, Statistics, and Event Data Records.

N2SVCD Components

The N2IWF is built on the N2SVCD framework. The following diagrams show the N2SVCD components which are deployed for a standard SCP deployment, and for a standard SIP deployment respectively: